I always find it easiest to move my position rather than to try and use the focusing ring... leaning in towards your subject is much easier.
Be aware though that the light is dramatically reduced through extension tubes, so if you have a bunch all connected together you may need to either reduce the number or increase the light on your subject.

Start with the smallest one. From my non-scientific research, most seem to get best use from it using a somewhat longer lens, in the 70-100mm length instead of a wider lens like a 20mm.

If you're using a tripod, a focus rail works best. Personally, I get some good results just manually focusing hand-held, then gently shifting my weight to get my subject in focus.

You'll find that your depth of field is EXTREMELY shallow. For instance, I shot a wasp on a flower, he was probably only 3/4 of an inch long, and when looking at the shot full-screen, you can see that the body was in sharp focus and the head/eyes was soft.

Here's the wasp shot I mentioned, note the shallow depth of field, and that was f/8. Hand-held, 1/800sec, ISO 400.

I've practiced on fixed subjects with a tripod (ice crystals on a window) and still find the focus extremely sensitive. I'm using 3 stacked tubes for a total of 65mm on a 100mm macro lens. Not familiar with the rail systems and would like to know how they mount. Lens collor with Acra swiss plate? Is the rail a better system for fixed subjects and focus stacking better for hand held moving?

I have a $13 US 2 way macro focus rail slider coming this week. I intend on using it for 3D photography but it is really designed for focusing macro images if Auto Focus doesn't work because of the reduction of light reaching the sensor when you use extension tubes or if AF doesn't work with your set of extension tubes..

I am thinking of ordering the same rail, but I am worry about dealing with an unknown outfit. (I have gotten burn while ordering from unknown website). Please let us know if the you got the order with no problems.

Thanks

Joe

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